If those experiments work — and there is no guarantee of that — they could have a profound influence on how other stores operate. Over time, they could also introduce new forms of automation, putting traditional retail jobs in jeopardy. At the same time, locating those stores close to customers' homes could also help Amazon further its ambitions of delivering internet orders within hours.

Latest developments: Amazon has opened a fifth book store, and is targeting India for grocery stores,but will start with 2 stores in Seattle and possibly a handful more in the U.S., but the plans are somewhat in flux as the company figures out the way ahead. An NYU professor explains: "What appears to be clear is they haven't yet zeroed in on a format they're willing to massively scale ... This is a company that the moment it figures out something that works, it puts nuclear energy behind it."